Detection of Antifreeze (Brine) Leakage into Wastewater

Importance of the Topic

The reliable identification of antifreeze compounds such as ethylene glycol and propylene glycol in industrial wastewater is essential to prevent environmental contamination and protect human health. Traditional UV detectors cannot differentiate antifreeze agents, and COD methods suffer from long measurement times and interference by inorganic salts. Total organic carbon (TOC) analysis offers a universal approach to monitoring organic carbon content, making it a promising tool for continuous detection of antifreeze leaks.

Objectives and Study Overview

This study demonstrates the capability of Shimadzu’s TOC-L laboratory analyzer and the TOC-4200 on-line analyzer to detect low to high concentrations of leaked antifreeze in wastewater. Key goals include evaluating TOC recovery accuracy, establishing calibration and correlation with COD values, and illustrating the feasibility of continuous on-line monitoring.

Methodology and Instrumentation

Six wastewater samples spiked with ethylene glycol to yield carbon concentrations of 0, 1, 5, 10, 20, and 50 mgC/L were prepared. TOC measurements were conducted using non-purgeable organic carbon (NPOC) analysis via 680 °C combustion catalytic oxidation. A two-point calibration with 0–60 mg/L potassium hydrogen phthalate ensured quantification accuracy. COD reference measurements followed JIS K 0102 standards.

Used Instrumentation

• Shimadzu TOC-L total organic carbon analyzer (laboratory)
• Shimadzu TOC-4200 on-line TOC analyzer

Main Results and Discussion

TOC recoveries for spiked samples ranged from 97.0 % to 100.2 %, demonstrating high accuracy across the full concentration range. The correlation between spiked and measured TOC concentrations yielded a coefficient of 0.9999. TOC and COD measurements also showed strong agreement (correlation coefficient 0.9995), indicating that TOC analysis can effectively replace COD for antifreeze detection.

Benefits and Practical Applications

• High sensitivity detection from trace to elevated concentrations of antifreeze agents.
• Rapid laboratory measurements with TOC-L for diverse applications including quality control and research.
• Continuous on-line monitoring with TOC-4200 at ten-minute cycles, enabling real-time wastewater surveillance.
• Single-instrument management of all organic contaminants without specificity limitations.

Future Trends and Potential Applications

Advances in on-line TOC analyzers will focus on integration with automated sampling systems, enhanced data analytics for early leak detection, and expansion into other industrial effluents. Combining TOC monitoring with predictive maintenance and IoT connectivity promises more proactive environmental management.

Conclusion

Shimadzu’s TOC-L and TOC-4200 analyzers provide accurate, efficient, and continuous methods for detecting antifreeze leakage in wastewater. Their strong correlation with established COD methods affirms TOC as a versatile tool for comprehensive organic contaminant management.

References

Shimadzu Corporation. Total Organic Carbon Analyzer TOC-L & On-line TOC Analyzer TOC-4200. First Edition Nov. 2024.